I suspect that like creationism and traducianism, the practical impact of these doctrines is seen not directly, but in the way that they safeguard and inform your views of other doctrines.
I was wondering how it might have practical implications, and this post was spot-on, in my opinion. God has been sovereign from eternity, and God's glory has always been the ultimate end of every motion of His will.
I believe supralapsarianism is the way to go, for when singular actions are considered and subdivided into different aspects, the order in which the aspects are carried out is the exact opposite of the order in which they are conceived. Thought always involves a consideration of the ends logically prior to the means; otherwise the means would be just "out there" detached from any particular end, and actions would be performed without any purpose.
For instance, if I wish to get some Taco Bell for dinner, I first think of the end, gaining Taco Bell, and then I think of how this Taco Bell can be obtained -- I'll have to drive -- and then I realize that in order to drive, I need to get car keys. When this plan is executed, I first get the keys, then I drive to Taco Bell, then I get the food, the exact opposite of the conceived plan. Likewise, since the creation of man ultimately serves to glorify God's mercy and justice through salvation and damnation, it follows that God's self-glorification via election and reprobation are considered as an end of creation (i.e. creation is the means of them), and therefore they are logically prior to creation.
It could be argued that God does not think discursively, but intuitively, but this objection ultimately fails. We subdivide other aspects of God's thought. We can speak of God's decrees elsewhere as distinct propositions without implying that He thinks discursively. Why not in the lapsarian debate? Lapsarianism does not imply that God thinks in this order, but rather that his thought,
when expressed in a way that condescends to human minds, can be accurately conceived in a specific order.